The present invention relates to a signal synthesizer circuit for synthesizing a signal whose magnitude is a sinusodial function having any arbitrary phase of an independent variable from two signals whose magnitudes are sinusoidal functions having different phases from each other of the independent variable such as, for example, a sine function and a corresponding cosine function (a phase difference of 90.degree.) of the independent variable, and a high-resolution positioning system making use of the signal synthesizer circuit.
Heretofore, in a manufacturing apparatus of semiconductor devices or in a industrial robot, a positioning operation has been effected to bring a loading table or an arm to a desired position. In such cases, in the positioning operation, open-loop control making use of a step-motor or the like and closed-loop control making use of a position detector and a D.C. motor have been employed in the prior art. However, as the required precision for positioning is enhanced, necessity of the closed-loop control is being increased.
As the position detector that is essentially necessitated for the closed-loop control, a magnetic scale, an optical encoder, a laser length meter, etc. have been known, and in the case of the magnetic scale, optical encoder or the like, normally a resolution of the order of about 1 micron can be obtained, while in the case of the laser length meter a resolution of the order of submicrons can be obtained. However, since the laser length meter is very expensive, it was difficult to provide a position detector having a resulution of the order of submicrons at a low cost and in a simple manner.